EarthTalk®

Dear EarthTalk: I’ve noticed that wildflower blooms in the mountains have been coming earlier and earlier in recent years. Is this a sign of global warming? And what does this mean for the long term survival of these hardy yet rare plants? — Ashley J., via e-mail

As always, it’s hard to pin specific year-to-year weather-variations and related phenomena—including altered blooming schedules for wildflowers—on global warming. But longer term analysis of seasonal flowering patterns and other natural events do indicate that global warming may be playing a role in how early wildflowers begin popping up in the high country.

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University of Maryland ecologist David Inouye has been studying wildflowers in the Rocky Mountains near Crested Butte, Colorado for four decades, and has noticed that blooms have indeed begun earlier over the last decade. Aspen sunflowers, among other charismatic high country wildflowers, used to first bloom in mid-May, but are now are doing so in mid-April, a full month earlier. Inouye thinks that smaller snow packs in the mountains are melting earlier due to global warming, in turn triggering early blooms.

Smaller snow packs not only mean fewer flowers (since they have less water to use in photosynthesis); they can also stress wildflower populations not accustomed to exposure to late-spring frost. According to Inouye’s research, between 1992 and 1998 such frosts killed about a third of the Aspen sunflower buds in some 30 different study plots; but more recently, from 1999 through 2006, the typical mortality rate doubled, with three-quarters of all buds killed by frost in an average year thanks to earlier blooming.

Inouye’s worrisome conclusions are backed up by experiments conducted by fellow researcher John Harte, who over a 15 year period used overhead heaters in nearby wildflower study plots to accelerate snow melt. The results were the same: Wildflowers bloomed early and not as vigorously.

Several studies in Europe have shown that some species of wildflowers there may be able to migrate north and to higher elevations as the climate warms, but Inouye fears his beloved Aspen sunflowers and many other American wildflowers may be lost forever as they are not able to migrate as quickly as needed in order to survive widespread surface temperature increases and escape extinction.

Harte is also gloomy about the prospects for Colorado’s mountain wildflowers. He predicts that the wildflower fields he and Inouye have been studying will give way to sagebrush desert within the next 50 years, whether or not the governments of the world can get a grip on greenhouse gas emissions.

As a hedge against such dire predictions, the nonprofit Center for Plant Conservation is spearheading seed collection efforts on thousands of rare wildflower species across the U.S. for inclusion in the Colorado-based National Center for Genetic Resources Preservation, a repository for both common and rare “prized” American plant seeds. The “banked” seeds, useful if not solely for preserving the genetic makeup of species that may go extinct in the wild, can also be used for future restoration projects on otherwise compromised landscapes.

Given the usual higher prices of organic versus conventionally-grown foods, it can be a challenge to get the biggest bang for our buck while eating healthy and avoiding the ingestion of synthetic chemicals along with our nutrients. One approach, say some experts, is to only buy organic when the actual edible parts of a non-organically grown food might come into direct contact with toxic fertilizers and pesticides.

The nonprofit Environmental Working Group (EWG) reports that consumers can reduce their chemical exposure by some 80 percent by either avoiding the most contaminated conventionally grown fruits and vegetables altogether, or by eating only the organic varieties. To help us sort through what and what not to buy, the group offers a handy Shopper’s Guide to Pesticides, which fits on a small piece of paper that you can keep in your pocket and have handy on grocery trips. You can print it out for free from EWG’s FoodNews.org website, or you can download it as a free App for your iPhone.

To make it easy to use, EWG has distilled its analysis into two lists. The first, “Dirty Dozen: Buy These Organic,” lists foods that when grown conventionally contain the largest amounts of pesticide and fertilizer residues. These include peaches, strawberries, apples, blueberries, nectarines, bell peppers, spinach, cherries, kale/collard, greens, potatoes, and (imported) grapes. Consumers should definitely spend the extra money for organic versions of these foods.

On the other side of the coin, EWG’s “Clean 15” list includes foods that contain the least amount of chemical residues when grown conventionally. These include onions, avocados, sweet corn, pineapples, mangos, sweet peas, asparagus, kiwi, cabbage, eggplant, cantaloupe, watermelon, grapefruit, sweet potatoes and honeydew. It’s OK to eat conventionally grown varieties of these foods.

EWG analysts developed the “Clean 15” guide using data from some 89,000 tests for pesticide residues in produce conducted between 2000 and 2008 and collected by the U.S. Department of Agriculture (USDA) and the U.S. Food and Drug Administration (FDA). What’s the difference, you may ask? EWG found that by eating five conventionally-grown fruits and vegetables a day from the Dirty Dozen list, a consumer on average ingests 10 different pesticides; those who stick to the Clean 15 list ingest less than two.

Other foods you and your family eat, such as meats, cereals, breads and dairy products, might also be exposing you to unwanted chemicals. According to EWG, the direct health benefits of organic meat, eggs and milk are less clear, but you should play it safe by sticking with all-natural, free-range, grass-fed meats that are not fed antibiotics or growth hormones, and by choosing only organic dairy products.

Thanks to increasing demand, more and more food purveyors are putting extra emphasis on organics. This will ultimately result in both lower prices and larger selections. Natural foods market aisles are already teeming with organic choices—and chances are your local supermarket or big box store has introduced organic versions of many popular items. Consequently, there has never been a better time to take stock of what you are feeding yourself and your family, and to make changes for better health.